Description :

Context and objectives

The project delivered a significant contribution to the water management problem solving in the Tarim river basin of the Xinjiang Province of the P.R. China. The Tarim river and basin forms one of the world’s largest closed hydrological drainage systems, forms ideal land for agriculture (e.g., cotton production), but suffers from reduced water availability. Since the 1950’s, excessive land reclamation, over-grazing, unreasonable utilization of water resources in the upper reaches of the basin in combination with temperature increase due to climate change, have intensified environmental deterioration. Since the 1970’s a strong dry-out of the lower region has been observed. This dry-out seriously deteriorated the basin’s downstream ecosystems, with an expanding desertification along the lower reaches of the river. In order to meet these problems, there is a strong need for integrated and sustainable water management planning in the region.
During Phase 1 of the project, a prototype decision support system has been set up based on linked river catchment hydrological and river hydrodynamic models. The 2nd phase of the project demonstrated that the prototype decision-support system can be applied for scenario-analysis in water management. Also training on the use of the system has been given to the local experts. The following set of scenarios were developed, implemented in the system, and the effects investigated on the Tarim river hydrology: climate change (global warming) till the 2050s and till about 2100, land use trends (historical since 1950 and projected till 2030), and upstream snow and glacier melting scenarios.

Methodology

In order to meet the objectives, the project has:
• analysed future trends (by global warming) in precipitation, temperature and potential evapotranspiration by statistically processing and downscaling of climate model simulation results (GCM runs of the IPCC AR4 archive);
• analysed the effects of these climate change trends in precipitation, temperature and potential evapotranspiration on the hydrology of the Tarim basin: on rainfall-runoff and river flow and stages, during high and low flow periods (floods and droughts), and on groundwater levels;
• analysed long-term changes in land cover over the Tarim basin by means of available remotely sensed data (LANDSAT TM/ETM+ and CORONA), and investigated the impact of these historical land use changes on the hydrology of the basin;
• developed future land use change scenarios based on the Moland CA model, and investigated the impact of these projected land use changes on the hydrology of the basin;
• analysed the effects of upstream snow and glacier melting scenarios on the hydrology of the basin.
The impact investigations on the Tarim basin hydrology were based on the combined hydrological – hydrodynamic models developed for the lower Tarim river and the Kaidu subbasins. In order to enable impact analysis of glacier melting, additional models were developed for the Hetian subbasin.